As the cultivation method of the paddy rice, a transplanting paddy rice culture which transplants raising seedling, and a direct sowing paddy rice culture which directly sows seeds have widely been known.
As the direct sowing paddy rice culture, a flooding direct sowing paddy rice culture or a dry field direct sowing paddy rice culture has been known. In addition, it has also been generally known a method in which iron powder, calcium peroxide or a molybdenum compound is coated onto a seed.
One of the great problems of the direct sowing paddy rice culture is to control weeds. The cultivation term of the direct sowing paddy rice culture is long as compared with that of the transplanting paddy rice culture, so that it is necessary to control weeds for a longer period of time. Therefore, a number of spreading a herbicide is many times which take much labor, so that labor-saving has been desired.
As a herbicide to be used in a paddy field, there have widely been known a bleaching herbicidal compound, an acetolactate synthase (hereinafter referred to as ALS) inhibitory-type herbicidal compound, a protoporphyrinogen oxidase (hereinafter referred to as PPO) inhibitory-type herbicidal compound and a very-long-chain fatty acid elongase (hereinafter referred to as VLCFAE) inhibitory-type herbicidal compound, etc.
The bleaching herbicidal compound is a well-known herbicidal compound, which kills weeds by whitening the weeds. As the bleaching herbicidal compound, for example, a pyrazole-based herbicidal compound and a triketone-based herbicidal compound have widely been known.
The pyrazole-based herbicidal compounds are, for example, pyrazolate, pyrazoxyfen and benzofenap, and are described in The Pesticide Manual 13th Edition, pp. 844-845, 848-849 and 81, respectively.
The triketone-based herbicidal compounds are, for example, mesotrione, sulcotrione and benzobicyclon, and are described in The Pesticide Manual 13th Edition, pp. 631-632, 908-909 and 80, respectively. In addition, tefuryltrione (CAS No. 473278-76-1) and bicyclopyrone (CAS No. 352010-68-5) are also the triketone-based herbicidal compounds.
Other than the pyrazole-based herbicidal compound and the triketone herbicidal compound, for example, clomazone (CAS No. 81777-89-1) or a compound 6-chloro-3-(2-cyclopropyl-6-methylphenoxy)pyridazin-4-yl morpholin-4-carboxylate (hereinafter also referred to as Compound (I)) represented by the following formula,
is also the bleaching herbicidal compound (Patent Document 1, Non-Patent Document 2).
The ALS inhibitory-type herbicidal compound is a well-known herbicidal compound, which kills weeds by inhibiting ALS whereby syntheses of valine, leucine and isoleucine which are essential amino acids are inhibited. As the ALS inhibitory-type herbicidal compound, for example, a sulfonylurea-based herbicidal compound, a pyrimidinylsalicylic acid-based herbicidal compound and a triazolopyrimidine-based herbicidal compound have widely been known.
The sulfonylurea-based herbicidal compounds are, for example, azimsulfuron, bensulfuron-methyl, cyclosulfamuron, halosulfuron-methyl, ethoxysulfuron, imazosulfuron, pyrazosulfuron-ethyl, chlorimuron-ethyl, cinosulfuron and metsulfuron-methyl, and are described in The Pesticide Manual 13th Edition, pp. 46-47, 73-74, 222-223, 523-524, 386-387, 560-561, 847-848, 161-162, 184-185 and 677-678, respectively. In addition, flucetosulfuron (CAS No. 412928-75-7), propylsulfuron (CAS No. 570415-88-2) and metazosulfuron (CAS No. 868680-84-6) are also the sulfonylurea-based herbicidal compounds.
The pyrimidinylsalicylic acid-based herbicidal compounds are, for example, bispyribac, pyribenzoxim, pyriftalid and pyriminobac-methyl, and are described in The Pesticide Manual 13th Edition, pp. 96-97, 852-853, 860-861 and 863-864, respectively. In addition, pyrimisulfan (CAS No. 221205-90-9) and triafamone (CAS No. 874195-61-6) are also the pyrimidinylsalicylic acid-based herbicidal compounds.
The triazolopyrimidine-based herbicidal compound is, for example, penoxsulam, and is described in The Pesticide Manual 13th Edition, pp. 753-754.
The PPO inhibitory-type herbicidal compound is a well-known herbicidal compound, which kills weeds by inhibiting PPO which causes browning symptoms. The PPO inhibitory-type herbicidal compounds are, for example, oxadiargyl, oxadiazon and pentoxazone, and are described in The Pesticide Manual 13th Edition, pp. 725-726, 727-728 and 757-758, respectively.
The VLCFAE inhibitory-type herbicidal compound is a well-known herbicidal compound, which kills weeds by inhibiting VLCFAE whereby synthesis of an aliphatic acid is inhibited. The VLCFA inhibitory-type herbicidal compounds are, for example, butachlor, pretilachlor, thenylchlor and mefenacet, and are described in The Pesticide Manual 13th Edition, pp. 118-120, 799-800, 956 and 621-622, respectively.
As a method for saving labor for spreading agricultural chemicals, there are seed treatments, and seeds to which a fungicide had been treated, seeds to which an insecticide had been treated and seeds to which a plant growth regulator had been treated have widely been known (Patent Documents 2 to 4). However, a paddy rice seed to which a herbicide had been treated has never been known. This is because different from a fungicide, an insecticide and a plant growth regulator which develop effects by absorbing these chemicals into a crop seed, whereas the herbicide an effect of which is developed by being absorbed by the weeds, by existing the herbicide used for the seed treatment at the neighbor of the seed with a high concentration, occurrence of chemical damage to the paddy rice itself becomes the problem and it is difficult to ensure a sufficient herbicidal effect at the portion apart from the seed. From such a background, a concept of treating a seed with a herbicide and controlling weeds by a seed treated by a herbicide is never thought for those skilled in the art.
Incidentally, with regard to the method for controlling weeds by plant seeds to which a herbicide has been treated, there is a description in a part of the publicly known documents, but there is neither specific description nor shown any Examples with regard to the method for controlling weeds by paddy rice seeds treated by a herbicide (Patent Documents 5 and 6).